Novel photoresist materials and photolithography process

ABSTRACT

A material for use in lithography processing includes a polymer that turns soluble to a base solution in response to reaction with acid and a plurality of magnetically amplified generators (MAGs) each having a magnetic element and each decomposing to form acid bonded with the magnetic element in response to radiation energy.

BACKGROUND

When the minimum feature size of an integrated circuit (IC) shrinks to250 nm or less, traditional photolithography technology has variousdifficulties to achieve high resolution in photoresist patterning. Forexample, shorter wavelength light such as deep ultraviolet (DUV)including 248 nm UV by krypton fluoride (KrF) excimer lasers and 193 nmUV by argon fluoride (ArF) excimer lasers are employed to realizepatterning integrated circuit features much smaller, such as those in130 nm, 90 nm, and 65 nm technology nodes. However, DUV radiation is notcompatible with many different types of photoresist. Correspondingly, anew type of photoresist material, referred to as chemical amplifiedresists (CAR), has been adopted for use with DUV. However, in CAR, photogenerated acid in exposed regions often diffuses into unexposed regions,causing blurring of the latent image and resulting in lateral bias ofthe exposed image.

It is desired to provide a new and improved system and process forsupporting DUV and other types of photolithography. It is also desiredto provide new photoresist materials that overcome one or more problemsassociated with conventional materials.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 is a flowchart of one embodiment of a method of lithographypatterning utilizing magnetically-amplified resist.

FIGS. 2 through 5 illustrate sectional views of one exemplarysemiconductor device utilizing magnetically-amplified resist duringvarious stages of a lithography patterning process.

FIG. 6 illustrates a schematic view of one embodiment of a lithographyapparatus designed for processing magnetically-amplified resist andutilizing the method of FIG. 1.

DETAILED DESCRIPTION

It is understood that the following disclosure provides many differentembodiments, or examples, capable of implementing different features ofthe invention. Specific examples of components and arrangements aredescribed below to simplify and thus clarify the present disclosure.These are, of course, merely examples and are not intended to belimiting. For example, the formation of a first feature over or on asecond feature in the description that follows may include embodimentsin which the first and second features are formed in direct contact, andmay also include embodiments in which additional features may be formedinterposing the first and second features, such that the first andsecond features may not be in direct contact. In addition, the presentdisclosure may repeat reference numerals and/or letters in the variousexamples. This repetition is for the purpose of simplicity and clarityand does not in itself dictate a relationship between the variousembodiments and/or configurations discussed.

FIG. 1 is a flowchart of one embodiment of a method 100 of lithographypatterning utilizing magnetically-amplified resist. FIGS. 2 through 5illustrate sectional views of one exemplary semiconductor device 200utilizing magnetically-amplified resist during various stages of alithography patterning process. FIG. 6 illustrates a schematic view ofone embodiment of a lithography apparatus 300 designed for processingmagnetically-amplified resist and utilizing the method 100. Withreference to FIGS. 1 through 6, the method 100, the semiconductor device200 fabricated thereby, the lithography apparatus 300, and themagnetically-amplified resist will be collectively described below.

Referring to FIG. 1 and FIG. 2, the method 100 is initiated at step 102by forming, on a substrate 210 of the semiconductor device 200, amagnetically-amplified resist (MAR) 220. The semiconductor device 200may be a semiconductor wafer or other suitable devices. In the presentembodiment, the substrate 210 may include silicon. The substrate mayalternatively include other suitable semiconductor material, includingGe, SiGe, or GaAs. The substrate may alternatively include anon-semiconductor material such as a glass plate forthin-film-transistor liquid crystal display (TFT-LCD) devices. Thesubstrate 210 may further include other materials such as low kdielectric material, oxide, and conductive material. The substrate 210may further include one or more material layers to be patterned.Additionally, the substrate 210 may include a bottom anti reflectingcoating (BARC).

MAR 220 is formed on the substrate 110. For example, MAR 220 may beformed on a BARC layer of the substrate 210. In the present embodiment,MAR 220 has a thickness ranging between about 50 angstroms and 5000angstroms. In another embodiment, MAR 220 may have a thickness rangingbetween about 500 angstroms and 2000 angstroms. The formation of MAR 220may be implemented by a technique such as spin-on coating and may befollowed by a soft baking process.

MAR 220 includes a polymer material that turns soluble to a developersuch as a base solution when the polymer is reacted with acid.Alternatively, MAR 220 includes a polymer material that turns insolubleto a developer such as a base solution when the polymer is reacted withacid. MAR 220 further includes a solvent filling inside the polymer. Thesolvent may be partially evaporated due to a prior baking process. TheMAR 220 also includes a magnetically-amplified generator (MAG) 230, withMAG molecules distributed inside the solvent and/or polymer. Whenabsorbing photo energy (or radiation energy), the MAG 230 decomposes andforms a small amount of acid bonded with a magnetic element (referred toas magnetic acid). In the present embodiment, MAG 230 includes apolycyclic aromatic group. MAG 230 may have a concentration rangingbetween about 1% and 20% wt of MAR 220. In the present embodiment, MAG230 is adopted as a replacement to a photo-acid generator (PAG) and isincorporated into polymer to form MAR 230. The magnetic element ischemically or otherwise bonded to MAG 230. Upon absorbing photo energy,the magnetic element is bonded to a corresponding acid formed from MAG.

The magnetic element may include an iron-containing magnetic chemicalgroup. In one embodiment, the magnetic element includes at least one ofFe₃O₄ and Fe₂O₃. In another embodiment, the magnetic element includes atransitional metal such as Fe₃O₄ and/or Fe₂O₃ doped with transitionalmetal ions. In another embodiment, the magnetic element includes atomsin 1A, 2A, or 3A groups of the Periodic Table of the Elements, such asNa, K, Mg, Ca, Al, or Ga. Alternatively, the magnetic element mayinclude Fe, Co, Ni, Sc, Ti, V, Cr, Mn, Cu, Zn, Na, K, Mg, Ca, Al, Ga,compounds thereof, or combinations thereof. The magnetic element mayhave a linear size ranging between about 0.1 micrometer and 10micrometer. The magnetic element may include a composite structure suchas an organic compound with iron oxide physically or otherwise bonded toor enclosed by the organic compound.

In furtherance of the present embodiment, MAR 220 also includes aquencher material (not shown) that distributes inside the solvent andpolymer. The quencher may be a base type and is capable of neutralizingacid. Collectively or alternatively, the quencher may inhibit otheractive component of MAR 220, such as inhibiting MAG 230 and acid. Thequencher may have a concentration ranging between 0.5% and 10% wt of MAR220. In one example, the quencher includes a magnetic element bondedthereto, similar to the magnetic element bonded to MAG 230.

Referring to FIG. 1 and FIG. 3, the method 100 proceeds to step 104 byexposing the MAR 230 to photo energy. At step 104 during aphotolithographic patterning process, MAR 220 is exposed to a radiationenergy such as deep ultra-violet (DUV) through a photomask (mask orreticle) having a predefined pattern, resulting in a resist pattern thatincludes a plurality of unexposed regions such as unexposed features 220a and a plurality of exposed regions such as exposed features 220 b. Theradiation energy may include a 193 nm beam by Argon Fluoride (ArF)excimer lasers, or a 157 nm beam by Fluoride (F2) excimer lasers. Theexposed MAG 230 in the MAR 220 is decomposed as anion and acid 240,resulting in the MAR being more soluble to water than unexposed MAR. Theacid 240 generated by photo energy from MAG 230 in the exposed regions220 a includes magnetic element bonded thereto, and is thereforereferred to as magnetic acid (MA) as mentioned above. The exposingprocess may be implemented by a lithography tool such as a scanner, astepper, a wet lithography tool, or a cluster tool capable of photoexposing and applying a magnetic field to MAR 220, which is furtherdescribed below.

Referring to FIGS. 1 and 4, the method 100 proceeds to step 106 byapplying a magnetic field 250 to MAR 220. The magnetic field is designedso that the magnetic acid 240 in the exposed regions of MAR 220 isdriven to move up and down substantially along a z-axis perpendicular tothe plane of the substrate 210. In the present embodiment, the magneticfield 250 changes directions up and down periodically or randomly, andhas a gradient in magnitude along the z-axis. In such a way, themagnetic acid is controlled to move up and down along the z-axis in theexposed regions of MAR 220 to cause chemical amplification, whichresults in more acid 245 being formed in the exposed regions, increasingthe solubility of MAR 230 of the exposed regions when placed in adeveloper. Since chemical amplification is introduced by (or partiallyintroduced by) the magnetic field 250 instead of a high temperaturebaking (such as a post exposure baking), lateral diffusion of themagnetic acid 240 is reduced. Furthermore, the chemical amplificationreaction duration is shortened. For example, the magnetic field 250applied to the MAR 220 may have a duration less than a few minutes, suchas somewhere between about 10 seconds and 60 seconds. As a result of theshortened duration, the diffusion of the magnetic acid 240 is furtherreduced and the diffusion of the acid 245 formed by the chemicalamplification is also reduced. The lithography patterning resolution isenhanced accordingly.

The magnetic field 250 can be provided by a magnet device or a clustertool such as a cluster lithography apparatus 300 schematicallyillustrated in FIG. 6. The cluster lithography apparatus 300 is designedto be operable to provide a magnetic field such as the magnetic field250 described above. The apparatus 300 includes a substrate stage 310designed to secure a substrate 320 to be processed by the apparatus 300for patterning. The substrate stage 310 is operable to move thesubstrate relative to the apparatus 300. For example, the substratestage 310 is capable of translational and/or rotational displacement forsubstrate alignment, stepping, and scanning. The substrate stage 310 mayinclude various components suitable to perform precise movement. Asubstrate to be held by the substrate stage 310 and processed by theapparatus 300 may be a semiconductor wafer such as the semiconductordevice 200.

The apparatus 300 includes one or more imaging lens systems (referred toas a “lens system”) 330. The substrate 320 may be positioned on thesubstrate stage 310 under the lens system 330. The lens system 330 mayfurther include or be integral to an illumination system (e.g., acondenser) which may have a single lens or multiple lenses and/or otherlens components. For example, the illumination system may includemicrolens arrays, shadow masks, and/or other structures. The lens system330 may further include an objective lens which may have a single lenselement or a plurality of lens elements. Each lens element may include atransparent substrate and may further include a plurality of coatinglayers. The transparent substrate may be a conventional objective lens,and may be made of fused silica (SiO2), calcium-fluoride (CaF2), lithiumfluoride (LiF), barium fluoride (BaF2), or other suitable material. Thematerials used for each lens element may be chosen based on thewavelength of light used in the lithography process to minimizeabsorption and scattering.

The apparatus 300 may include an immersion fluid retaining module 340designed for holding an immersion fluid 350 and/or other proper fluidsuch as a cleaning fluid. The module 340 may be positioned proximate(such as around) the lens system 330 and designed for other functions,in addition to holding the immersion fluid. The immersion fluid to beutilized in the apparatus 300 may include water (water solution orde-ionized water-DIW), gas, or other suitable fluid. The module 340 mayinclude various apertures (or nozzles) for providing an immersion fluidfor an exposure process, and/or performing other proper functions. Forexample, the module 340 may include an aperture 342 as an immersionfluid inlet to provide and transfer the immersion fluid into a spacebetween the lens system 330 and the substrate 320 on the substrate stage310.

The apparatus 300 may further include a radiation source. The radiationsource may be a suitable ultraviolet (UV) or extra UV(EUV) light source.For example, the radiation source may be a mercury lamp having awavelength of 436 nm (G-line) or 365 nm (I-line); a Krypton Fluoride(KrF) excimer laser with wavelength of 248 nm; an Argon Fluoride (ArF)excimer laser with a wavelength of 193 nm; a Fluoride (F2) excimer laserwith a wavelength of 157 nm; or other light sources having a desiredwavelength (e.g., below approximately 100 nm). The apparatus 300 mayinclude a chamber to provide a vacuum environment or a low pressureenvironment with inert gas for protecting various components and asubstrate to be processed.

The apparatus 300 may include a photomask for use during a lithographyprocess. The mask may include a transparent substrate and a patternedabsorption layer. The transparent substrate may use fused silica (SiO2)relatively free of defects, such as borosilicate glass and soda-limeglass. The transparent substrate may use calcium fluoride and/or othersuitable materials. The patterned absorption layer may be formed using aplurality of processes and a plurality of materials, such as depositinga metal film made with chromium (Cr) and iron oxide, or an inorganicfilm made with MoSi, ZrSiO, SiN, and/or TiN.

In the present embodiment, the apparatus 300 includes a magnetic module360 designed to provide a magnetic field, such as the magnetic field 250in FIG. 4, to a substrate on the substrate stage 310. The magneticmodule 360 is mechanically attached to the apparatus 300. In the presentembodiment, the magnetic module 360 is attached to the module 340. Themagnetic module 360 may include conductive parts or conductive wiresproperly designed and configured according to the requirement of themagnetic field 250. The magnetic module 360 may further include or becoupled to an electric power supply to provide the conductive parts orwires with electric current in proper magnitude and frequency in orderto realize the magnetic field 250. For example, a conductive wireconfigured around the module 340 as a magnetic solenoid as illustratedin FIG. 6. The apparatus 300 described above can provide the magneticfield 250 to the magnetic acid 240 in the exposed regions of the MAR 220at step 106. The apparatus 300 can also be used to perform exposingprocess to the MAR 220 at step 104. Alternatively, steps 104 and 106 maybe combined to be implemented concurrently to MAR 220. The apparatus 300may further include a module to provide high temperature for baking asubstrate on the substrate stage 310.

Referring to step 106 of the method 100, a baking process may beadditionally implemented before, during, and/or after the application ofthe magnetic field 250 to the MAR 220 at step 106. The accompanyingbaking process may have a temperature lower and a duration less thanthose of a conventional post exposure baking process for enhancedperformance and accelerated throughput.

Referring to FIGS. 1 and 5, the method 100 then proceeds to step 108 todevelop the MAR layer 220 in a developer. The MAR in the exposed regionsare substantially dissolved. The developer may be a tetramethylammoniumhydroxide (TMAH) based solution. As one alternative, magnetic elementmay be bonded to the developer in chemical or ionic bond, in order toneutralize or eliminate magnetic element in the MAR layer 220 after thedeveloping process. The method 100 may further include other processingsteps after the developing of MAR 220 at step 108, such as baking,etching/implanting, and/or stripping the MAR layer.

The present disclosure provides a material, a method, and an apparatusfor lithography patterning. The present disclosure may have variousvariations without departure from the spirit of the present disclosure.In one example, the apparatus 300 may be reduced to only provide themagnetic field and perform step 106 of the method 100. In anotherexample, the apparatus 300 may be reduced to provide both a hightemperature and a magnetic field to the MAR layer on a substrate. Inother embodiments for implementing the disclosed material, method,and/or apparatus, it is not limited to patterning a semiconductorsubstrate. Other substrate such as a glass substrate for TFT_LCDdevices, or a transparent substrate (such as fused quartz) for photomaskmay be patterned using the disclosed material, method, and apparatus. Inanother variation, the exposing process at step 104 may be implementedby techniques such as maskless photolithography, x-ray lithography,electron-beam writing, or ion-beam writing.

As an alternative to the disclosed material, method, and apparatus,ferroelectric material may be utilized. The alternative material,referred to as electrically amplified resist, includes a polymermaterial that turns soluble to a developer such as a base solution whenthe polymer is reacted with acid; a solvent filling inside the polymer;and an electrically-amplified generator (EAG). EAG molecules aredistributed inside the solvent and/or polymer. When absorbing photoenergy, the EAG decomposes and forms a small amount of acid withelectric element (referred to as electric acid). The electric elementmay be other proper material with electric dipole moment in addition toferroelectric material and is chemically or otherwise bonded to EAG. Inthe alternative method, step 106 will be replaced by applying anelectric field to the electrically-amplified resist layer. The electricfield is designed operable to drive the electric acid up and down alongthe z-axis perpendicular to the substrate plane, resulting in chemicalamplification to form more acid in the exposed regions of theelectrically-amplified resist. The alternative apparatus is designed toprovide an electric field, instead of a magnetic field, along the z-axiswith proper magnitude and frequency capable of driving electric acidaccordingly.

Thus, the present disclosure provide a material for use in lithographyprocessing. The material includes a polymer that turns soluble to a basesolution in response to reaction with acid; and a plurality ofmagnetically amplified generators (MAGs) each having a magnetic elementand decomposes to form acid bonded with the magnetic element in responseto radiation energy.

In some embodiments, the magnetic element may include an iron-containingmagnetic chemical group. In other embodiments, the magnetic element mayinclude at least one of Fe₃O₄ and Fe₂O₃. The magnetic element mayinclude at least one of Fe₃O₄ and Fe₂O₃ doped with transitional metalions. The magnetic element may include a group selected from the groupconsisting of Fe, Co, Ni, Sc, Ti, V, Cr, Mn, Cu, Zn, Na, K, Mg, Ca, Al,Ga, compounds thereof, and combinations thereof. The magnetic elementmay have a linear size ranging between about 0.1 micrometer and 10micrometer. The magnetic element may include a composite structure. Themagnetic element may be chemically bonded to one of the plurality ofMAGs. The material may further include a plurality of quenchers that arecapable of neutralizing acid. The plurality of quenchers may includesecond magnetic element bonded thereto. The plurality of MAGs each mayinclude a polycyclic aromatic group.

The present disclosure also provide a method for photolithography. Themethod includes forming a photo sensitive layer on a substrate. Thephoto sensitive layer includes a polymer that turns soluble to a basesolution in response to reaction with acid; and a plurality ofmagnetically amplified generators (MAGs) that decompose to form acidassociated with magnetic elements in response to radiation energy. Themethod further includes exposing the photo sensitive layer to aradiation energy; applying a magnetic field to the photo sensitive layeron the substrate; and developing the exposed photo sensitive layer.

In some embodiments, the applying of the magnetic field may includeapplying a magnetic field perpendicular to the substrate. The applyingof the magnetic field may include applying an alternating magnetic fieldchanging amplitude and direction at a predefined frequency. The formingof the photo sensitive layer may include forming the photo sensitivelayer in a multilevel structure. The method may further include bakingthe photo sensitive layer between the exposing and the developing steps.The baking may occur at least partially concurrent with the applying themagnetic field. The substrate may be selected from the group consistingof a semiconductor substrate, a photomask substrate, andthin-film-transistor liquid-crystal-display (TFT-LCD) substrate. Theexposing of the photo sensitive layer may include performing theexposing in an immersion lithography environment.

The present disclosure also provides an apparatus for lithographyprocessing. The apparatus includes a chamber; a substrate stage in thechamber operable to hold a substrate; and a magnetic module configuredto provide a magnetic field to the substrate on the substrate stage. Insome embodiments, the apparatus may further includes a radiation energysource; and an objective lens configured to receive radiation energyform the radiation energy source and direct the radiation energy towardthe substrate positioned on the substrate stage. The magnetic module maybe designed to provide the magnetic field tunable and alternating. Themagnetic module may be configured to provide the magnetic fieldperpendicular to a substrate positioned on the substrate stage. Theapparatus may further include a baking module to heat a substratepositioned on the substrate stage. The apparatus may further include afluid module configured to provide a fluid and hold thereof forimmersion lithography processing.

The foregoing has outlined features of several embodiments so that thoseskilled in the art may better understand the detailed description thatfollows. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions andalterations herein without departing from the spirit and scope of thepresent disclosure.

1. A material for use in lithography processing, comprising: a polymerthat turns soluble to a base solution in response to reaction with acid;and a plurality of magnetically amplified generators (MAGs) each havinga magnetic element and each configured to decompose to form acid bondedwith the magnetic element in response to a radiation energy.
 2. Thematerial of claim 1, wherein the magnetic element comprises aniron-containing magnetic chemical group.
 3. The material of claim 1,wherein the magnetic element comprises at least one of Fe₃O₄ and Fe₂O₃.4. The material of claim 1, wherein the magnetic element comprises atleast one of Fe₃O₄ and Fe₂O₃ doped with transitional metal ions.
 5. Thematerial of claim 1, wherein the magnetic element comprises a componentselected from the group consisting of Fe, Co, Ni, Sc, Ti, V, Cr, Mn, Cu,Zn, Na, K, Mg, Ca, Al, Ga, compounds thereof, and combinations thereof.6. The material of claim 1, wherein the magnetic element has a linearsize ranging between about 0.1 micrometer and 10 micrometer.
 7. Thematerial of claim 1, wherein the magnetic element comprises a compositestructure.
 8. The material of claim 1, wherein the magnetic element ischemically bonded to one of the plurality of MAGs.
 9. The material ofclaim 1, further comprising a plurality of quenchers that are capable ofneutralizing acid.
 10. The material of claim 9, wherein the plurality ofquenchers comprise second magnetic elements bonded thereto.
 11. Thematerial of claim 1, wherein the plurality of MAGs each comprises apolycyclic aromatic group.
 12. A method for photolithography,comprising: forming a photo sensitive layer on a substrate, the photosensitive layer including: a polymer that turns soluble to a basesolution in response to reaction with acid; and a plurality ofmagnetically amplified generators (MAGs) that decompose to form acidassociated with magnetic elements in response to radiation energy;exposing the photo sensitive layer to a radiation energy; applying amagnetic field to the photo sensitive layer on the substrate; anddeveloping the exposed photo sensitive layer.
 13. The method of claim12, wherein the application of the magnetic field comprises applying amagnetic field perpendicular to the substrate.
 14. The method of claim12, wherein the application of the magnetic field comprises applying analternating magnetic field changing amplitude and direction at apredefined frequency.
 15. The method of claim 12, wherein the formationof the photo sensitive layer comprises forming the photo sensitive layerin a multilevel structure.
 16. The method of claim 12, furthercomprising: baking the photo sensitive layer between the exposing andthe developing steps.
 17. The method of claim 16, wherein the bakingoccurs at least partially concurrent with the applying the magneticfield.
 18. The method of claim 12, wherein the substrate is selectedfrom the group consisting of a semiconductor substrate, a photomasksubstrate, and thin-film-transistor liquid-crystal-display (TFT-LCD)substrate.
 19. The method of claim 12, wherein the exposing of the photosensitive layer comprises performing the exposing in an immersionlithography environment.
 20. An apparatus for lithography processing,comprising: a chamber; a substrate stage in the chamber operable to holda substrate; and a magnetic module configured to provide a magneticfield to the substrate on the substrate stage.
 21. The apparatus ofclaim 20, further comprising: a radiation energy source; and anobjective lens configured to receive radiation energy form the radiationenergy source and direct the radiation energy toward the substratepositioned on the substrate stage.
 22. The apparatus of claim 20,wherein the magnetic module is configured to provide the magnetic fieldin a tunable and alternating configuration.
 23. The apparatus of claim20, wherein the magnetic module is configured to provide the magneticfield perpendicular to a substrate positioned on the substrate stage.24. The apparatus of claim 20, further comprising a baking module toheat a substrate positioned on the substrate stage.
 25. The apparatus ofclaim 20, further comprising a fluid module configured to provide afluid and hold thereof for immersion lithography processing.